However, he's certainly a musician who's taken every step needed to reach such a momentous platform, having already played sold-out shows in Wembley Stadium and Madison Square Garden; reaching out now to an audience that may not necessarily be fans seems like the natural next step.
"I'm actually more excited for this than I was for my Wembley Stadium shows because when you're playing your own [shows] you're not really winning anyone over, because they've already parted with cash to buy a ticket," he told the BBC.
"But I think I'm going to be playing to a lot of people who might have heard some of my songs on the radio, but they're Glastonbury-goers, they're not fans of me. Knowing that there are people in the audience who possibly don't even like my music at all and are just there to sort of see, that excites me."
To celebrate, we tracked the 10 most important moments in Sheeran's career from debut artist to Glastonbury headliner.
'The A Team' released - 12 June, 2011
Sheeran made an early splash with his debut single, 'The A Team', becoming a global top 10 hit and earning the musician his first Grammy nomination for Song of the Year. The song is intended as a ballad about a prostitute addicted to crack cocaine, inspired by Sheeran's visit to a homeless shelter where he heard several personal stories from its occupants.
His early success also saw him headline the BBC Introducing tent at that year's Glastonbury Festival.
+ released - 9 September, 2011
Though he'd previously released multiple EPs, the increasing hype from 'The A Team' meant his debut studio album + secured himself within the musical mainstream. It debuted straight at the top of the UK Albums Chart with first-week sales exceeding 102,000 copies, and still stands as the 8th best-selling album of the decade in the UK.
First two Brit Awards - 21 February, 2012
Any artist arriving on this level of hype was bound to make a splash when it came to awards season: Sheeran was the night's top winner, alongside Adele, at 2012's Brit Awards. He picked up both Best British Male Solo Artist and Best Breakthrough Act, beating out the likes of Anna Calvi, Emeli Sandé, Jessie J, and The Vaccines for the latter honour.
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Co-vocals on Taylor Swift's 'Everything Has Changed' - 16 July, 2013
Taylor Swift first contacted Sheeran after hearing his music while on tour in Australia, with the pair writing 'Everything has Changed' in Swift's own backyard. Another of Sheeran's trademark guitar ballads, the song was released as the sixth single from Swift's Red.
Madison Square Garden shows - October, 2013
Sheeran supported both Taylor Swift and Snow Patrol on their tours, while launching his own US tour of 6,000 - 9,000 capacity venues in late 2012 and early 2013. However, the truly defining moment for the singer-songwriter was his run of three sold-out shows at New York City's Madison Square Garden, where he debuted new song 'Tenerife Sea'.
x released - 20 June, 2014
His second studio album became an instant international success, where his debut had been more of a slowburner; it hit the number one spot in 15 different countries, with its lead single 'Sing' marking Sheeran's first number one song in the UK.
It was also Spotify's most-streamed album of the year, all while becoming the third best-selling album of the decade in the UK; it also picked up double Grammy nominations, and a Brit Award win for Best British Album of the Year.
Wembley Stadium shows - July, 2015
Sheeran launched a world tour to promote x, with the culmination being three sold-out dates at Wembley Stadium between 10-12 July 2015, at a 90,000-person capacity. These shows were the subject of their own documentary, entitled Jumpers for Goalposts: Live at Wembley Stadium.
The concert also aired on NBC as a one-hour special, with the inclusion of special behind-the-scenes footage.
Though he'd received five Grammy nominations in the past, not including his contributions to Swift's Red, it was thanks to his third single from x, 'Thinking Out Loud', that Sheeran finally landed his first wins. The track won both Song of the Year and Best Solo Pop Performance.
÷ released - 3 March, 2017
After a long, self-imposed hiatus - both from music and from social media - Sheeran sent the internet wild by posting a simple blue square, which fans knew heralded the coming of his third album. ÷ was a record-breaking hit: it was the fastest-selling album by a male artist in the UK, after selling 672,000 copies in the first week, and the highest opening behind Adele's 25 and Oasis' Be Here Now.
It also broke the record for the most top ten songs from a single album on the UK Singles Chart; heavy streaming contributed to all 16 tracks entering the top 20, which led some commentators to call for a re-consideration of how charts are compiled.
Member of the Order of the British Empire (MBE) - 16 June, 2017
Royal approval certainly isn't necessary for a headlining slot at Glastonbury, but it certainly helps.
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